holoprosencephaly

[hŏl′ō-prŏs′ĕn-sĕfə-lē, hō′lō-]
n.
  1. Failure of the forebrain to divide into hemispheres or lobes causing insufficient development of facial characteristics such as the nose, lips, and palate; in severe cases, cyclopia can occur.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.